The main goal of this study is to identify proteins recovered from human uterine luminal washes that are distinct from serum and unique to the secretory phase of the menstrual cycle. Such putative progesterone-dependent proteins will be characterized and evaluated as markers of progesterone dependence of endometrial neoplasia and as useful tools to further study the molecular mechanism of progesterone action. A computer-assisted scanning method has been used to identify and quantify proteins in 2-dimensional chromatograms of washings obtained from the human uterine lumen. In addition, in vitro incubation of human endometrial glands has made it possible to distinguish endometrial products from serum proteins, to identify cycle-specific components, and to detect proteins that are dependent upon the addition of steroid hormones to the medium. Labeled amino acids and inhibitors of protein synthesis are being used and released in in vitro experiments in order to distinguish secretions from other media proteins. Proteins released into the media by endometrial cancer cell lines are being studied. We have found what may be a distinctive marker protein for this type of malignancy. Purification of proteins of interest will be performed in order to generate specific antisera for assay purposes. Sera will be collected from patients with endometrial cancer and screened for marker protein.